Preoperative Internal Medicine Consultation for Elective Intermediate-to-high Risk Noncardiac Surgery in Ontario

• Main Author: Wijeysundera, Duminda
• Other Authors: Laupacis, Andreas
• Language: en_ca
• Published: 2010
• Subjects: Perioperative medicine; Preoperative consultation; Surgery; Internal medicine; 0564
• Online Access: http://hdl.handle.net/1807/26338

This dissertation uses population-based administrative healthcare data to evaluate the outcomes, processes-of-care and practice variation associated with preoperative medical consultation in Ontario, Canada. First, a multicentre cross-sectional study was conducted to develop a novel algorithm for identifying preoperative medical consultations using administrative data. The optimal claims-based algorithm was a physician service claim for a consultation by a cardiologist, general internist, endocrinologist, geriatrician, or nephrologist within 120 days before the index surgery. This algorithm had a sensitivity of 90% (95% confidence interval [CI], 86 to 93) and specificity of 92% (95% CI, 88 to 95). Second, we conducted a population-based cohort study to evaluate the association of preoperative medical consultation with outcomes and processes-of-care. After adjustment for measured confounders using propensity-score methods, consultation was associated with increased preoperative testing, preoperative pharmacological interventions, 30-day mortality [relative risk (RR) 1.16; 95% CI, 1.07 to 1.25], 1-year mortality (RR 1.08; 95% CI, 1.04 to 1.12), and mean hospital stay (difference 0.67 days; 95% CI, 0.59 to 0.76). These findings were stable across subgroups, as well as sensitivity analyses that tested for unmeasured confounding. Third, temporal trends and practice variation in consultation were evaluated within the population-based cohort. The proportion of patients undergoing consultation remained relatively stable over the study period, at approximately 39%. Although patient-level and surgery-level factors did predict consultation use, they explained only 6.8% of variation in consultation rates. By comparison, inter-hospital differences in rates were substantial (range, 1.9% to 86.8%), were not explained by surgical volume or teaching status, and persisted after adjustment for patient-level and surgery-level factors. Overall, this dissertation highlights the need for research to identify interventions for safely decreasing perioperative risk, define mechanisms by which consultation influences outcomes, examine factors that influence practice variation in medical consultation, and identify patients who benefit most from preoperative medical consultation.